Preface

PVC profile extrusion mold is the core of the extrusion line. Its technical status is directly related to the stability of extrusion production, the quality of extrusion products, extrusion production efficiency, and the service life of the die itself. After the production and use of the mould for a period of time, due to the different wall pressure and resistance of the material at different positions of the section inside the extrusion die, uneven wear will occur, which will lead to material deviation, product forming size exceeding the standard, uneven wall thickness, bending and other quality defects. At the same time, in the use of the mold, due to improper loading and unloading, cleaning, maintenance, will also cause the extrusion die working surface and decomposition surface rust, smoothness decline, the joint part of the flow channel generated dead Angle. As a result extrude PVC profile appearance is coarse, or produce material retention and paste, make production difficult to continue. Therefore, the correct use and maintenance of PVC profile extrusion mold is very important.

Use of Die

1.Assembly and installation of die

During the assembly of the die, clean the fitting surface of each part and the positioning pin hole (use copper tools when necessary, and try not to use emery cloth). Take the connector as the base part and gradually carry out the assembly. When assembling, the positioning pin should be wiped clean, coated with a little silicon oil, and gently tap the screw part, coated with a little high-temperature resistant oil. There should be no gap between the plates after assembly, and the die gap should not change significantly.

Before the die is installed, install a flange, install a transition sleeve (porous plate) at the exit end of the extruder, and butt the die head with the extruder. Carefully calibrate the levelness and verticality of the upper plane and outlet surface of the die before tightening the screws. Screw should be tightened diagonally alternately. Finally, check the distance between the two flanges, all sides should be equal.

After the die is installed, install the heating plate and thermocouple probe. Good contact shall be maintained between the heating plate and the mold, and between the probe and the bottom surface of the temperature measuring hole.

When the die is heated up, generally divided into two parts. First rise to 130°C, keep warm for 15~20 minutes, tighten the screws again. Then heat it up to the working temperature and keep it warm for about 5 minutes.

Start at low speed, and then speed up after stable discharge. Section observation after the material plasticization reaches the ideal state. If the discharging is uniform and the plasticization is good, then could do haul-off work.

2.Remove and clean the die

Clean material should be added before stopping. Stop the machine after the cleaning material is extruded from the die. Loosen the connection screw properly and remove the heating plate. Remove the whole piece of the die or remove the screw directly, pry up the die plate from both sides of the upturned mouth with copper rod. While removing the die plate, clean the materials in the mold cavity and between the die plate by means of needle-nosed pliers, copper needle, cotton yarn and compressed air. After the mold is cooled (polishing the cavity surface if necessary), it shall be assembled into a whole piece, and the outlet surface shall be sealed with linoleum paper and then sent to the mold room for safekeeping.

When the machine is shut down under non-abnormal conditions, the cleaning material in the mold does not need to be cleaned. If the production task is not finished, the mold can not be removed.

Use of vacuum mold

1. Installation of vacuum mold

The vacuum forming die is placed on the cavity surface of the forming block and kept in the same plane. If the front of the tank has sealing requirements, the tank should be close to the mold. Connect the vacuum, water inlet and outlet pipes.

2.Use of vacuum mold

Before doing haul-off work, check the cavity surface of the mold and the vacuum mold for foreign matter, such as material debris or dust, etc. (rinse well with water). Under the condition of good material elasticity, it is recommended not to open the mold for haul-off work, so as to reduce the damage to the mold by disassembly. When the mold is stuck and the template needs to be removed, it should be handled gently to avoid bumps and scratches. The residue in the mold can be knocked out with a wooden or copper rod. The foreign matter and precipitates in vacuum tank can be removed by copper needle and copper sheet. When the channel is blocked, the compressed air can be dredged, or removing the plug screw to clean up.

Number

Faults

Reason

Method for correction

1

There are scratches on the surface of profiles

1. There are foreign bodies in the calibrator mold cavity

2 .There are collisions and scratches on the forming surface of the calibrator cavity or watertank plates

3 .There are knocks and bruises on the cavity surface of the die

1. Removal of foreign bodies

2. Repair and Polish mold

3. Repair and Polish mold

2

Poor surface gloss

1. Improper temperature setting, excessive or insufficient plasticization of materials

2. Material stagnation in neck, bushing or die

3. Mixed with different batches, brands of resin

4.Problems in Matching and Mixing Procedures

5. The forming plate of die and calibrator are not clean.

1. Check the actual temperature of each measuring point and adjust it

2. Clean up after shutdown and polish the adhesive

3. Should be avoided

4. Check mixer, strictly follow the process

5. Inspection and Polish mold

3

The product wall thickness and size of matching part change or fluctuate

1. The feed fluctuates

2. Uneven mixing of materials

3. The heating plate is not working properly

4. Mold gap changes

5. There is material stagnation in die head

6. The haul-off unit skidded

7. The speed of the haul-off unit fluctuates

1. Improve the fluidity of powder, check and adjust the temperature of feed section

2. Strictly implement mixing process

3. Inspection, maintenance or replacement

4. Re-assembly and inspection after mould cleaning

5. Mold cleaning

6. Strengthen the Compression Force

7. Inspection and repair

4

Section irregularity of profiles

1. Overpressure of the haul-off unit

2. Uneven discharge of die

3. The vacuum system is blocked

4. Vacuum pump pumping capacity is insufficient

5. Insufficient cooling capacity

6. Vacuum water tank has poor cooling and setting effect

1. Adjust appropriately

2. Slice inspection, mould cleaning and polishing

3. Inspection and cleaning

4. Inspection and repair

5. Clean up waterways, lower water temperature or lower traction speed

6. Improve the sealing effect of water tank, increase supply and pumping capacity

5

Bending and Deformation of Profiles

1. Mould or production line is not straight

2. Cooling imbalance

3. Insufficient cooling capacity

4. Asynchronism of Up and Down Traction of the haul-off unit

5. Uneven discharge of die

6. The resistance of the forming surface of the calibrator mold is not balanced

1. Adjust to a straight line

2. Strengthen convex cooling capacity

3. Increase water supply and reduce water temperature

4. Check and adjust

5. Check slices, clean and polish moulds

6. Maintenance under the guidance of professionals

6

Local contraction scar

1. Cross surface such as inner rib discharging slow

2. Poor vacuum-pumping effect

3. Local cooling is too fast

1. Cleaning and polishing

2. Check, clean up

3. Turn down the cooling water

7

The product has the bubble, the surface has the spot or the fish eye

1. Excessive moisture and volatile content in materials

2. Blockage of main engine vacuum system

3. The setting of material thermal stability is on the high side

4. High screw temperature setting

5. Screw heat conduction oil path is not good or the oil quantity is not enough

6. Excessive extrusion speed

1. Drying, make volatile less than 0.1%.

2. Check and clean up

3. Check the quality of heat stabilizer or adjust the formulation

4. adjustment

5. Inspection and maintenance

6. Appropriate reduction of extrusion speed

8

Abnormal Paste in die

1. Cavity surface smoothness is poor

2. The transition plane is not smooth enough

3. High temperature setting

4. Poor thermal stability of materials

1. Mold cleaning and polishing

2. correction

3. Check and adjust

4. Check and adjust